Hey guys i was watching on a TV program the other night. A chinese or japanese samurai fighter used the method of shouting at an opponent, which made the water in his body ripple, and it knocked him down!? Is this true??

Because the sound waves were projected out of his mouth..towards the opponent?

They would have needed to start in his larynx, and so would have done far more damage to his throat than to anyone nearby. Once the sound waves leave his mouth they travel out in an arc, dissipating their energy over a larger area. So as cool as the Samurai killer shout sounds, I'm afraid it's not true.